Stargazin Antibody (Rabbit mAb) [D18F22]

Stargazin, also known as TARP γ‑2, is a four‑pass transmembrane AMPA receptor regulatory protein that acts as an auxiliary subunit of neuronal AMPA receptors, coupling biosynthetic trafficking, synaptic targeting and channel gating to activity-dependent forms of glutamatergic synaptic plasticity. The protein has a small extracellular loop and a cytoplasmic C‑terminal tail containing PDZ‑binding and phosphorylation motifs, an arrangement that allows its ectodomain to contact AMPA receptor ligand-binding domains while the intracellular tail engages postsynaptic scaffolds such as PSD‑95 and signaling pathways that control receptor movement and retention. Direct interaction between stargazin and AMPA receptor subunits promotes exit of receptor complexes from the endoplasmic reticulum, surface delivery and stabilization at postsynaptic sites, and disruption of this interaction in stargazer mutant mice leads to severe loss of synaptic AMPARs with preserved extrasynaptic receptors, demonstrating a specific requirement for stargazin in compartment-selective synaptic targeting. Functionally, stargazin modifies AMPA receptor gating by slowing channel deactivation and desensitization and increasing the rate of channel opening, effects that prolong and enhance synaptic currents; the cytoplasmic tail predominantly controls trafficking and desensitization, whereas the first extracellular loop makes a larger contribution to agonist efficacy, indicating that distinct stargazin regions separately tune receptor kinetics and localization. Expression of stargazin in neurons produces a marked reduction in glutamate-evoked desensitization and a substantial increase in responses to the partial agonist kainate, consistent with an allosteric interaction that destabilizes the desensitized state and boosts gating efficacy across diverse AMPA receptor subunit compositions. At synapses, stargazin interacts with PSD‑95 via its C‑terminal PDZ motif to cluster AMPARs and regulate their synaptic retention, and phosphorylation of this tail modulates binding to PSD‑95 and lateral mobility in the membrane, thereby controlling activity-dependent insertion and removal of AMPARs during plasticity. In cerebellar stellate cells, stargazin is required for compartment-specific AMPA receptor trafficking and activity-dependent changes in rectification that reflect shifts in AMPAR subunit composition; stargazer mutant stellate cells show severely diminished AMPAR-mediated synaptic transmission, reduced rectification index and impaired plasticity, while extrasynaptic AMPARs remain, underscoring a key role for stargazin in synapse-specific regulation rather than global receptor expression. Stargazin also participates in NMDA-dependent long-term depression by regulating both endocytosis of synaptic AMPARs and their recycling/forward transport, placing it at the center of bidirectional trafficking pathways that weaken synaptic strength in response to defined patterns of activity. The original stargazer mouse phenotype—cerebellar ataxia and absence epilepsy—is caused by a recessive mutation that silences stargazin expression, leading to loss of AMPARs at cerebellar synapses and reduced postsynaptic L‑type CaV1.2 channel expression, suggesting that stargazin coordinates assembly or trafficking of AMPA receptor–calcium channel complexes important for motor coordination and rhythmic cortical–thalamic activity. The auxiliary subunit structure, defined ectodomain and tail functions, roles in ER exit, synaptic targeting, kinetic modulation, and cerebellar/higher brain circuit plasticity make stargazin a mechanistically rich target for evaluating AMPA receptor–dependent signaling in learning, ataxia, epilepsy and related pathologies.

• [1] Tomita S, et al. Nature. 2005 Jun 23;435(7045):1052-8.
• [2] Jackson AC, et al. J Neurosci. 2011 Mar 16;31(11):3939-52.